1. Field of the Invention
The present invention relates to a tonometer and, more particularly, to a non-contact tonometer for spraying a compressive fluid on an eye to be examined to deform the cornea and measuring the intraocular pressure of the eye to be examined in accordance with a deformed state of the cornea.
2. Related Background Art
A conventional non-contact tonometer of this type generally uses air as the compressive fluid. For example, as disclosed in Japanese Laid-Open Patent Application Nos. 54-38437 and 61-321, air in a compression chamber is gradually compressed by a piston driven by a solenoid, and the compressed air is sprayed on the cornea of the eye to be examined through a nozzle to measure a period of time required to cause the cornea to assume a predetermined aplanation condition, thereby obtaining the intraocular pressure of the eye to be examined.
However, the solenoid or a solenoid driving power supply for driving the piston to deform the cornea within a very short period of time requires a relatively large force. Therefore, a conventional tonometer tends to be large and bulky.
Recent demand has arisen for a more compact, simpler tonometer.